Used to extend an array and copy it. This is used to propagate paths recursively.
First part.
The value to be aadded into the array.
A new array with all items from arr and newValue (which is last).
Used to extend an array and copy it. This is used to propagate paths recursively.
Param: arr
First part.
Param: newValue
The value to be aadded into the array.
Returns
A new array with all items from arr and newValue (which is last).